Valuation and Qualifying Accounts and Reserves (Details) (USD $)	12 Months Ended
	Jul. 31, 2013		Jul. 31, 2012		Jul. 31, 2011
Allowance for Doubtful Accounts, Current [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at beginning of period	$ 1,588,000		$ 1,220,000		$ 1,127,000
Charged to cost and expenses	(422,000)	[1]	458,000	[1]	244,000	[1]
Charged to other accounts - describe	0		0		0
Transfers (deductions) - describe	(563,000)	[2]	(90,000)	[2]	(151,000)	[2]
Balance at end of period	603,000		1,588,000		1,220,000
Inventory Reserves [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at beginning of period	16,286,000		13,316,000		13,791,000
Charged to cost and expenses	2,810,000	[3]	3,862,000	[3]	4,091,000	[3]
Charged to other accounts - describe	0		2,776,000	[4]	0
Transfers (deductions) - describe	(2,870,000)	[5]	(3,668,000)	[5]	(4,566,000)	[5]
Balance at end of period	16,226,000		16,286,000		13,316,000
Valuation Allowance for Deferred Tax Assets [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at beginning of period	1,162,000		1,162,000		1,162,000
Charged to cost and expenses	1,063,000	[6]	0		0
Charged to other accounts - describe	0		0		0
Transfers (deductions) - describe	0		0		0
Balance at end of period	$ 2,225,000		$ 1,162,000		$ 1,162,000

[1] (A)(Benefit from) provision for doubtful accounts.

[2] (B)Write-off of uncollectible receivables.

[3] (C)Provision for excess and obsolete inventory.

[4] (D)Reclassification of contract loss accrued in fiscal 2011.

[5] (E)Write-off of inventory.

[6] (F)Change in valuation allowance.